Can a variable frequency drive help an airline slash the use of energy in its flight simulators? When British Airways wanted to cut the energy consumption of its flight simulator cells, an approach it used involved implementing variable frequency drive (VFD) technology. The airline’s training center at Heathrow Airport uses a total of 18 flight simulators to train its own flight crews as well as crews from other major passenger airlines and cargo carriers.

Energy saving program drives change

The center is managed by a facility that has set up an energy saving program throughout Heathrow Airport. Because the training center uses more power than most other operations in the airport, airport managers figured investing in energy saving technologies would help slash emissions and improve the airport’s overall carbon footprint. The VFDs helped in this endeavor by reducing the energy use of the motor-driven fans located in each simulator cell.

What’s in a flight simulator?

Each flight simulator is a self-contained cell that incorporates a specialized computer and a hydraulics room for driving the simulator, as well as a dedicated environmental control system that maintains the optimal ambient temperature by cooling the entire cell area via an air-handling system.

Environmental control system is critical

Needless to say, the environmental control system is critical because it directly affects the comfort of trainers and crews as well as helps ensure that all equipment operates efficiently. For example, each simulator uses projectors to create the high-definition 3D images that trainees see through the “cockpit” windows. The equipment projects images onto a curved mirror mounted in the body of the simulator with a thin layer of Mylar and held in place by a vacuum. Should the ambient temperature go out of spec, it might affect the vacuum pump’s operation, which, in turn, could adversely affect the image’s magnification, clarity and realism.

Each air handling system uses a fan driven by a 15 horsepower (HP) motor to draw air into air ducts. The air then passes through a pre-heater and then either a cooling or heating battery, depending on ambient temperatures. In addition, an extraction fan sized between 5 and 20 HP works in recirculation ductwork to maintain atmospheric pressure in the cell. A series of dampers controls the air flow and draws in outside air when the outside temperature is low, letting the system benefit from the “free” cooling effect.

Energy inefficiency drives simulator improvement

Previously, fans in the air-handling system were driven continuously at maximum speed, regardless of system demand. This approach was energy inefficient and resulted in wear and tear on components such as motor bearings, drive shafts and belts. British Airways engineers therefore decided to improve the simulator cells.

A better approach

As part of the simulator upgrade effort, engineers redesigned the air handling system. They retained the original fan motors but replaced the original drives with Parker AC650V variable speed drives interconnected with a management unit. The approach let the fans be driven slowly when the weather was cooler, with the capability of running at maximum output during warm weather. The drives are designed to be easy to configure, even in complex open-loop applications, and provide a wide range of power outputs and options. The unit’s modular design makes it easy for engineers to make later changes to the control panels.

British Airways appreciated that Parker manufactures in the UK and offers local technical support. This is important because the simulators must run 24/7 so the capability to have immediate access to replacement parts is critical.

AC drives deliver payback

The modified air handling systems fitted with the AC650V drives are using significantly less energy. In fact, the technology has reduced each cell’s energy usage by 95 percent as well as let them cut costs in other areas as well. For example, the motor bearings don’t wear nearly as much, freeing the facility from having to perform maintenance as often. In addition, because the air handling units run at low speeds most of the time, the there is less overall noise in the simulator cells, which results in improved working conditions. Perhaps most importantly, the variable speed drives are cost-effective and thereby have provided a payback period of under two years.